An investigation will be undertaken into the possible occurrence of a new group of tetrahydroisoquinoline alkaloids in mammals under conditions of aberrant dopa metabolism. These alkaloids exemplified by norlaudanosolinecarboxylic acid and 1,2-dehydronorlaudanosoline appear to be formed in vivo by spontaneous non-enzymatic condensation of 3-4-dihydroxyphenylpyruvic acid and dopamine. Rats are being maintained on high daily dosages of dopa with and without inhibitors of enzymes of dopa metabolism and various tissue and excretions are being examined for the occurrence of norlaudanosolinecarboxylic acid, 1,2-dehydro-norlaudanosoline, and their catabolites. Similar in vitro studies are being conducted with isolate liver, brain, kidney, and adrenal cortex tissue. If norlaudanosolinecarboxylic acid and 1,2-dehydronorlaudanosoline induce significant inhibition of dopa and dopamine metabolism in vivo, their effect on such specific enzymes as dopa decarboxylase, tyrosine transaminase and tyrosine hydroxylase will be investigated. BIBLIOGRAPHIC REFERENCES: C. J. Coscia, W. Burke, G. Jamroz, A. Kosloff, J. McFarlane, J. Mitchell, and M. L. Wilson. Occurrence of a New Class of Tetrahydroisoquinolines in L-Dopa Treated Parkinsonian Patients. Fed. Proc. 36, 2804, 1977.